🚀 go-pugleaf

In article <4btc01$iok@ixnews8.ix.netcom.com>,
John DeFiore  <john_de@ix.netcom.com> wrote:

	[Re "breakeven" time for PV panels ]

>Well, maybe-  But let's count the energy used to mine and refine the
>materials needed, the transportation cost to the fab, auxiliary cost of
>the fab itself (obviously "amortized" over the life of the fab)  energy
>to run the fab and get the workers there, packaging costs,
>transportation cost to the end user, all the energy costs associated
>with hooking up the system and fabricating an inverter (manufacturing
>of the parts involved) or power management system, and the energy cost
>of running and maintaining the array.  I have seen a calculation that
>shows these costs being more than the total output of the cell over
>it's life.  Granted, amorphous cells will do better, and the realism of
>that calculation is open to question, but if you are considering the
>total energy input into the final system, it is not easily dismissable
>as bullshit to question the payback.

Only claim I had ever seen for energy payback was something on the
order of ~10 years for single-crystal down to ~1.? years for thin-film.

This probably did not include the guy on the production line with the
large boom-box or the traffic snarl on the interstate that the delivery
truck got caught in, but presumably these peripheral costs would yield
most readily to optimization as production increased. Given a 10-12
year warranty period and some reasonable life expectancy past that,
it would seem that it would take some fairly creative accounting to
show an energy loss.

Barry's original assumption of 20% efficiency sounds mildly optimistic,
but figuring 100-120 Watts/M**2, times 4-6 hrs insolation-multiplier/day,
times 10-20 years useful life, times storage/conversion efficiencies of
70-90%, I think you arrive at a lifetime production value of between
1 and 4.5 megawatt/hours of electricity per square meter of PV. (Better
estimates appreciated).

If you or anyone else have a general recollection of the calculations
of energy investment that you have seen, I would be extremely interested
in both the totals and a breakdown of principal components.

Rob Kleinschmidt